33-year-old parcel delivery guy is a real-life Good Will Hunting

Good Will Hunting is the story of a school janitor who also happens to be a math genius. It’s a fictional tale starring Matt Damon who has no formal education, but somehow demonstrates the natural skills required to solve the most complex of math problems. Now this fictional story has become a real story in China.

The real-life equivalent of Matt Damon is a 33-year-old man named Yu Jianchun. He works for a parcel delivery company and has no college degree, and yet he’s created an alternative proof for verifying Carmichael numbers. What are Carmichael numbers? Wikipedia is your friend here for a detailed explanation, but in summary they are not prime numbers but still pass Fermat’s primality test, making it more complicated to prove a number is actually prime.

The excellent Numberphile video below also offers a great explanation:

Carmichael numbers were verified with a proof written 20 years ago by a group of academics. Since then variations have been created, but they all follow the same base proof. What Yu has done is to create a completely different proof that’s much more efficient, which is incredible considering he’s done it all on his own with no specific math education.

Yu describes himself as shy, introverted, and diligent. He explains that he has a sensitivity to numbers and spends long periods of time in solitude with a calculator going over numbers. He wrote the proof during 2015 in his spare time and as he built himself a house in the village where he lives.

So far Yu has presented his proof and several other problem solutions during a graduate student seminar at Zhejiang University last month. His proof is being verified, but is already going to be included in a book written by Professor Cai Tinxin of Zhejiang University. Yu has also been offered a new job at a local silk manufacturer that has promised him more free time to study. Depending on how his proof verification goes, he may not need to take the new job or even keep his old parcel delivery gig.

This story originally appeared on Geek.